On Thu, 2018-04-05 at 22:06 -0400, Wakko Warner wrote: > I know now why scsi_print_command isn't doing anything. cmd->cmnd is null. > I added a dev_printk in scsi_print_command where the 2 if statements return. > Logs: > [ 29.866415] sr 3:0:0:0: cmd->cmnd is NULL That's something that should never happen. As one can see in scsi_setup_scsi_cmnd() and scsi_setup_fs_cmnd() both functions initialize that pointer. Since I have not yet been able to reproduce myself what you reported, would it be possible for you to bisect this issue? You will need to follow something like the following procedure (see also https://git-scm.com/docs/git-bisect): git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git bisect start git bisect bad v4.10 git bisect good v4.9 and then build the kernel, install it, boot the kernel and test it. Depending on the result, run either git bisect bad or git bisect good and keep going until git bisect comes to a conclusion. This can take an hour or more. Bart.